Waukesha CountyPower Outage History
What this grade means
Average — typical outage frequency and duration nationally. This county sits in the middle of the national distribution — its outage frequency and duration over the past 12 years are close to the nationwide median, neither notably better nor worse than most other US counties. A typical amount of backup-power preparedness is reasonable here.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Aug 11, 2021 | <1 hr | 45,425 (27%) | Thunderstorm Wind |
| Aug 11, 2021 | <1 hr | 42,687 (26%) | Thunderstorm Wind |
| Aug 11, 2021 | <1 hr | 41,617 (25%) | Thunderstorm Wind |
| Aug 11, 2021 | <1 hr | 37,922 (23%) | Thunderstorm Wind |
| Aug 11, 2021 | 6 hrs | 36,584 (22%) | Thunderstorm Wind |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Waukesha County, Wisconsin that day.
Over the 12 years from 2014 to 2025, Waukesha County recorded 1,243 distinct power outage events, averaging 3.2 hours per event.
The single worst outage on record in Waukesha County started August 11, 2021 (Thunderstorm Wind), lasting less than 1 hour and leaving up to 45,425 customers without power (27% of the county) at its peak.
July has historically been the worst month for outages in Waukesha County, with 176 events recorded during that month across the dataset.
Based on this history, Waukesha County earns a Reliability Grade of C, placing it in the 42nd percentile nationally for grid reliability (higher percentile = more reliable).
Similar counties in Wisconsin
Counties with the closest reliability grade and national percentile to Waukesha County.
| County | Grade | National percentile |
|---|---|---|
| Door County | C | 42nd |
| Portage County | C | 42nd |
| Waupaca County | C | 44th |
| Sawyer County | C | 44th |
| Jefferson County | C | 46th |
Most reliable counties nationally
The top 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | South Dakota | A | 100th |
| Clearwater County | Minnesota | A | 99th |
| Limestone County | Alabama | A | 99th |
Least reliable counties nationally
The bottom 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | West Virginia | F | 0th |
| Lincoln County | West Virginia | F | 0th |
| Cameron Parish | Louisiana | F | 0th |
FAQ
How often does power go out in Waukesha County?
Between 2014 and 2025, Waukesha County recorded 1,243 outage events, averaging 3.2 hours each.
What is Waukesha County's reliability grade?
Waukesha County has a Reliability Grade of C, in the 42nd national percentile.
What was the worst power outage in Waukesha County?
The worst outage on record started August 11, 2021 (Thunderstorm Wind), lasting less than 1 hour and affecting up to 45,425 customers.